Radionuclide and Colloid Migration Experiments in Quarried Block of Granite under In-Situ Conditions at a Depth of 240 m

Abstract

Radionuclide migration experiments in quarried blocks of granite under in-situ conditions at the 240-m level in AECL's Underground Research Laboratory (URL) were performed under a five-year cooperative research program between Japan Atomic Energy Research Institute (JAERI, reorganized to Japan Atomic Energy Agency, JAEA) and Atomic Energy of Canada Ltd. (AECL). Migration experiments with Br, 3 H, 85 Sr, 237 Np, 238 Pu, 95m Tc and synthetic colloids, and post-experimental alpha and gamma scanning of the fracture surfaces were performed using 1m 3 granite blocks, containing a single fracture, excavated from a water-bearing fracture zone. The transport of the radionuclides was affected by macroscopic mechanical dispersion, matrix diffusion and element-specific sorption on fracture surfaces. Colloid transport exhibited a complicated process that may include sedimentation and diffusion into stagnant zones.

Dissolved and Colloidal Transport of Cesium in Natural Discrete Fractures

“…However, the use of clay particles to investigate colloid‐associated Cs transport through fractures is relatively rare despite these particles' high abundance in natural systems (Möri et al, 2003). Considering the well‐known importance of fractures as favorable routes for colloids (McKay et al, 1993; McKay et al, 2002; Weisbrod et al, 2002; Zvikelsky and Weisbrod, 2006) and the existence of radioactive waste sites or potential repositories and nuclear facilities on fractured formations (Baek and Pitt, 1996; Vandergraaf et al, 1997; Möri et al, 2003; Missana et al, 2008; Yamaguchi et al, 2008), understanding colloid‐facilitated transport of Cs through fractures is of the utmost relevance.…”

Colloid-Facilitated Radionuclide Transport: Current State of Knowledge from a Nuclear Waste Repository Risk Assessment Perspective

“…For obvious reasons there have been no direct observations of colloid-facilitated radionuclide transport from deep geologic nuclear waste repositories, but there have been numerous laboratory studies conducted to better understand the risks associated with colloid-facilitated transport from such repositories. A majority of these have been conducted in Europe in association with national nuclear waste disposal programs (see Zänker andHennig, 2014, andDenecke, 2011), although work has also been conducted in the U.S. (Dittrich et al, 2015;Wang et al, 2015;Zavarin et al, 2012;Begg et al, 2013;Begg et al, 2015), Canada (Vilks and Baik, 2001), Japan (Yamaguchi et al, 2008), and more recently China (Xie et al, 2014;Lin et al, 2014;Xie et al, 2013a;Xie et al, 2013b). It goes beyond the scope of this report to summarize all the various laboratory studies on colloid-facilitated radionuclide transport that have been conducted.…”

Long-Term Chemical Alteration of 238Pu-Doped Borosilicate Glass in a Simulated Geological Environment with Bentonite Buffer

“…Experiments with trace amounts of radionuclides were performed in several underground research facilities (URF) [19][20][21], however, experiments with real vitrified radioactive waste were not yet performed in URF. Up to now, laboratory scale leaching and alteration tests is the only possibility to study complex interactions between the solidified waste, buffer, and host rock in static and dynamic conditions.…”